Navien NCB300-28K, Service Manual

Page: 100 / 108

Inspection and Maintenance Schedule 99
1. Press the Power button ( ) on the front panel to turn off
the boiler.
2. Disconnect the power supply to the boiler.
3. Turn off both gas and water supply to the boiler.
Note
Wait at least 30 minutes for the heat exchanger to
cool down.
4. Unfasten the 2 latches (at the top) and remove 2 screws (at
the bottom) to remove the front cover to gain access to the
internal components.
5. Once the front cover is removed, place it in a safe location to
prevent accidental damage.
Checking the CO₂
1. Check the CO₂ readings at full load and low load.
2. Check the CO readings and combustion performance
(CO/CO₂ ratio).
3. Check the CO readings and combustion performance.
For more information, refer to the 15th step in “4.3 Gas
Conversion” on page 21. The combustion reading (CO/CO₂
ratio) must be less than 0.004.
4. If the combustion reading (CO/CO₂ ratio) is greater than
this, and the integrity of the complete flue system and
combustion circuit seals has been verified, and the inlet gas
pressure and gas rate are satisfactory either:
●
Perform the full service. For more information, refer to
“8.5.2 Full Service” on page 99.
●
Set the Gas Valve. For more information, refer to “4.2
Measuring the Incoming Gas Pressure” on page 20.
Review with the Owner
1. Review the User’s Information Manual with the owner.
2. Emphasize the need to perform the maintenance schedule.
3. Remind the owner of the need to call a licensed contractor
should the boiler or system exhibit any unusual behaviour.
4. Remind the owner to follow the proper shutdown procedure
and to schedule an annual start-up at the beginning of the
next heating season.
5. After servicing, complete the relevant Service Interval
Record section of the Benchmark Checklist located on the
inside back page of this document.
8.5.2 Full Service
For reasons of safety and economy, it is recommended that the
boiler is serviced annually. Servicing must be performed by a
competent person in accordance with BS 7967-4. After servicing,
complete the relevant Service Interval Record section of the
Benchmark Checklist located on the inside back page of this
document.
Note
Where a full service is required, refer to “8.5.1 Interim
Service” on page 97.